Why should I avoid eating right before bed as a teen?

Eating right before you go to bed is a problem for two reasons. The first is that you don't have any opportunity to burn off the calories you've eaten before sleeping, so they are absorbed into your blood and transported around your body, where they are eventually stored as fat. The second problem is that, while you may be able to fall asleep right away, the digestive processes going on in your stomach will require your brain to be partly awake, making your sleep much less restful and deep.